• seatbelts
• misclassification
• imputation

In a recent letter, Cummings and Rivara¹ misstate my point regarding changes in estimated belt effectiveness in the mid-1980s using the comparison of front seat occupant pairs. They cite my statement, “What is not explained by the theory [about misclassification of seatbelt use by police] is the sudden gap in police reported use by the dead and survivors that appeared in the mid-1980s”² as faulting them for not explaining why prevalence of seatbelt use changed from 1975 to 1998. How could anyone who uses the English language with a modicum of proficiency interpret “sudden” as 23 years and “gap in police reported use by the dead and survivors” as general prevalence of belt use?

Actually, a cursory look at the graph in Cummings paper that I critiqued indicates that the major reduction in risk ratios indicative of seatbelt effectiveness occurred during a short period in the mid-1980s when belt use laws were being debated and initially enacted in a few states. I noted that this debate could have changed police behavior …